The invention relates to data transport over a Synchronous Optical Network (SONET) and, in particular, to an apparatus and method for transporting IP datagrams over SONET to link IP-based applications at high data rates with guaranteed quality of service.
In recent years, the telecommunications industry has been attempting to develop a network architecture that will support currently provided services as well as future IP-based multimedia applications. Currently, voice services are provided using traditional Time Division Multiplex (TDM) networks, which support real-time communications by means of switched circuits. Data services, such as Internet traffic, rely on a packet switching technology that uses a store-and-forward mechanism. Network providers and data service providers are concerned about having to manage two types of traffic, especially managing two separate networks. A further evidence of concern is that the exponential explosion of Internet traffic has shown that IP routing equipment causes a transfer bottleneck. The ever increasing network complexity is also becoming an important issue.
A trend today is to network services remotely in server farms. Consequently, network providers require new and cost effective technologies for interconnecting server farms with Internet Points of Presence (POPs).
This presents a twofold challenge. First, providing QOS to both required services such as Dynamic Naming System (DNS) as well as new value added services such as multimedia and WEB hosting. Second, providing reliable and cost effective transport from remote server farms to the POPs.
Such industry trends indicate a need for a change from traditional voice-dominant traffic networking to data-dominant traffic networking. Current proliferation of multimedia applications exert a high demand for end-to-end connections of a high Quality-of-Service (QoS). Services such as teleconferencing, video, voice and hi-fi audio are bandwidth consumers and delay intolerant. Therefore a connection of a high QoS, is one which guarantees a transport bandwidth and a deterministic signal propagation delay factor. Bandwidth utilization over the network is also closely related to profitability. Consequently, an efficient solution is required for managing bandwidth utilization.
Asynchronous Transfer Mode (ATM) has been proposed as a solution to all problems for voice and data services. As the implementation of ATM has progressed, however, it is clear that the advances promised for ATM have not been fulfilled. Rather, problems with traffic management, which ATM was supposed to eliminate in the first place, have become more and more apparent. Furthermore, IP over ATM does not appear to be an economical combination of protocols. It is unlikely that ATM will cope with the future IP-based applications that require high QoS.
Packet over SONET (POS) is a new and emerging technology attracting a lot of attention from both the telecommunications and data industries. The idea is to use SONET as a scalable and super-reliable physical transport medium to carry IP traffic, and IP technology to provide all services, including teleconferencing, voice, video, hi-fi audio, e-mail, news, etc. From an initial perspective, POS seems to be a very attractive solution, but the issue regarding QoS still needs to be addressed because POS is currently based on a shared environment.
There therefore exists a need for a way of implementing Packet over SONET that can guarantee the QoS that the current implementations of POS cannot.
It is an object of the present invention to provide centralized dynamic bandwidth management over a SONET domain that adapts to different types of traffic in real time.
It is a further object of the invention to provide transport of data traffic over a SONET domain characterized by a deterministic end-to-end delay.
It is another object of the invention to guarantee transport bandwidth over a SONET domain to packet based services.
It is another object of the invention to guarantee bandwidth and a deterministic end-to-end delay to IP based services transported through a SONET domain.
It is another object of the invention to provide guaranteed QoS for data traffic over a SONET domain through careful centralized bandwidth management.
It is a another object of the invention to provide guaranteed QoS for data traffic over a SONET domain shared with voice traffic.
It is another object of the invention to provide a programmable transport node bridging connections between an IP network to a SONET domain.
It is another object of the invention to provide a hardware interface for multiplexing IP packets into SONET frames and de-multiplexing IP packets from SONET frames.
It is another object of the invention to provide a scalable solution for IP traffic transport of high QoS over SONET.
It is another object of the invention to provide a reliable transport solution for data transfer between server farms and POPs using SONET which incorporates high QoS bandwidth management.
It is another object of the invention to provide a bandwidth management solution that accommodates high QoS data transport over interconnected SONET domains forming a network.
It is yet another object of the invention to provide a single bandwidth management protocol for data transport at high QoS for IP services across interconnected SONET domains forming a network.
In accordance with a first aspect of the invention, there is provided a method of transporting Internet Protocol (IP) datagrams received from an IP network through a Synchronous Optical Network (SONET) with a quality of service characterized by a deterministic end-to-end transfer delay in the SONET network, comprising the steps of:
accepting at a node in the SONET network a connection request from an IP service seeking to transfer datagrams through the SONET network;
formulating a management message to request a bandwidth allocation in response to the connection request;
sending the management message to a bandwidth allocation manager for the SONET network; and
assigning the connection to a channel for transporting the datagrams if the bandwidth allocation manager grants an allocation of the bandwidth for the connection request.
In accordance with a further aspect of the invention, there is provided apparatus for transporting IP datagrams received from an IP network through a SONET with a quality of service characterized by a deterministic end-to-end transfer delay in the SONET network, comprising:
a plurality of SONET nodes interconnected by at least one optical fiber ring, each of the SONET nodes including a transport protocol interface for receiving the IP datagrams from the IP network, a driver entity for passing the IP datagrams to a High Level Data Link Controller (HDLC) which provides a minimum level of framing for IP datagrams, a Field Programmable Gate Array (FPGA) for generating timing signals for the HDLC and for performing an Add/Drop function to insert datagrams into and extract datagrams from SONET frames; and
a one of the SONET nodes being further adapted to serve as a bandwidth manager to track usage of containers for transporting the datagrams within the SONET network.
A bandwidth management protocol and hardware are employed to achieve a multilevel control hierarchy for real time dynamic bandwidth management over SONET to provide Quality of Service characterized by a guaranteed bandwidth and a deterministic end-to-end delay for IP services. The control hierarchy is divided between control of inter- and intra-domain data traffic.
For intra-domain data traffic, bandwidth management is divided between bandwidth clients and a bandwidth allocation manager. A messaging protocol is provided for intra-domain data traffic which provides for real time dynamic bandwidth allocation including: election of a bandwidth allocation manager for a domain, re-election in the case of bandwidth allocation manager malfunction, allocation of bandwidth for connection-less traffic, setting-up new QoS connections, real time dynamic adjustment of the bandwidth for QoS connections, and connection tear down.
For inter-domain data traffic the bandwidth management is divided between bandwidth allocation managers of the domains. A messaging protocol is provided for inter-domain data traffic which provides for real time dynamic bandwidth allocation including: setting-up new QoS connections, real time dynamic adjustment of the bandwidth for QoS connections and connection tear down. Requests for QoS connections made by a bandwidth manager of a remote domain are passed to the bandwidth manager of a local domain through the bandwidth clients which route data between the two domains. The requests made to the local manager by the remote manager are made by the local bandwidth client that routes the traffic from the remote domain on behalf of the remote bandwidth manager.
A hardware interface bridges an IP network to a SONET domain. The hardware interface multiplexes IP packets into SONET frames and demultiplexes IP packets from SONET frames. IP packets are transported under the control of the local bandwidth client associated with the node. QoS connections of guaranteed bandwidth and deterministic end-to-end delay for IP services are thus provided.
Scalability on the SONET domain is implemented through the addition of extra optical links between the nodes in the domain which requires increased data throughput.